In the modern era, kidney transplantation is a safe and effective treatment for many patients with kidney failure. However, choosing the right patients for kidney transplantation is difficult, especially among older patients. Although older patients who receive transplants survive longer than if they had stayed on dialysis, still very few older patients are placed on the transplant waiting list. This is because no tools exist for determining risk in older patients undergoing transplantation, so clinical decision making has to be based on subjective perceptions of a patient's strength and reserve. Misclassification of these factors by the patient or provider likely results in decreased access to transplantation in a population that stands to greatly benefit from this treatment. Although transplant outcomes and survival benefit are similar in men and women, it has been well established that women have significantly less access to transplantation than men. We recently showed that this disparity is strongest in older patients, with older women having 30-60% less access than their male counterparts. However, it remains unclear whether patient or provider level factors contribute to this disparity. In this study we will explore differences by gender and age in factors influencing a patient's decision and ability to pursue transplantation. We will then use a new technique to explore the potential role of gender and age biases in a provider's choice to refer a patient for transplantation. Understanding the root causes of this gender/age disparity is crucial to developing interventions to improve access to transplantation, and healthcare in general, for women and older adults. PUBLIC HEALTH RELEVANCE: Although kidney transplantation is safe, effective, and life-extending for many patients, women have significantly less access to transplantation than their male counterparts, and we have shown that this disparity is widest among older women compared with older men. It is unknown whether this happens because of patient-level barriers to seeking transplantation or because of provider-level biases against referral of women compared with men. Since over 50% of dialysis patients are over the age of 65, equal access to transplantation for this subgroup is important;the goal of this project is to explore potential sources of the gender disparity in access to transplantation, and access to healthcare in general, so that interventions to minimize this disparity can be designed.